Neither snow, nor rain nor gloom of night will keep the e-mail from making its appointed rounds. Unfortunately, over 90 percent of that e-mail is complete junk, so perhaps if it were just a little bit afraid of the dark, we wouldn't be drowning in so much spam.

Because you can't exactly turn off the e-mail stream, the best way to get control of your messaging problems is to invest in an e-mail security appliance. In theory, an appliance could be dropped into any network, one hop before the server, and with a minimum amount of setup, start filtering the mail so only clean, approved messages are delivered to users.

The GCN Lab tested six e-mail gateway appliances in our Washington test center. The boxes were graded on how much spam and virus-laden e-mail they could catch on a simulated government network of 300 users (see our sidebar for more on the testing methodology).

The appliances were also evaluated on how easy they were to set up and maintain. Last year, in our first testing of e-mail appliances, some of the top performers required engineers to spend days tweaking and testing the devices. This year, we were looking for fire-and-forget solutions for overtaxed network administrators.

It's been our experience that e-mail security is more art than science, regardless of what vendors might tell you. As a result, the more time you spend with an appliance, the better your virus and spam protection. (Which, incidentally, is why enterprises might consider outsourcing mail filtering to companies such as Postini Inc., when appropriate. You give up some hands-on control but someone else's technicians handle signature updates, tweaks and so forth.)

We were looking at out-of-the-box performance, and we found that it can vary. Our two Review's Choice appliances, the Barracuda Spam Firewall 400 and Symantec Mail Security 8240, for instance, could fall into your mail stream tomorrow and provide excellent protection.

But we found that a cutting-edge appliance such as the IronPort C100 needs some attention before its best technology, in this case reputation-based filters, is at its best.

In other words, your next choice of an e-mail security appliance could be determined by your resources and experience with the technology. The good news is that if all you want to do is plug and play, there are products out there you can trust.